Reformer Tube Reference Markings for Creep Strain Measurement

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Solution Overview

Problem

Current methods for determining diametrical growth and remaining service life of tubular reactors in steam methane reforming processes face challenges due to inaccuracies in diameter measurements caused by thermal and mechanical stresses, leading to potential erroneous calculations of creep strain and premature replacements.

Innovation Solution

A method involving the provision of circumferential reference markings on the inner or outer surfaces of the reformer tubes, made during manufacturing or before service, to facilitate accurate alignment and measurement of diameter changes over time, using these markings to ensure consistent axial locations for reliable creep strain calculation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional diameter measurement methods are used without reference markings, then measurement process is simpler, but measurement precision deteriorates due to misalignment and thermal-mechanical stress-induced inaccuracies

Engineering Contradiction:

Improvediameter measurement accuracyVSAvoidmeasurement system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Circumferential reference markings are applied to the reformer tube during manufacturing or before service, establishing fixed reference points in advance. These markings remain stable under thermal and mechanical stresses, enabling accurate alignment and measurement of diameter changes at later inspection times without requiring complex real-time calibration procedures

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The circumferential reference markings serve as intermediary reference features that mediate between the measurement system and the reformer tube. These markings provide stable, detectable features that facilitate precise alignment and measurement of diameter changes without requiring direct complex interactions between the measurement device and the tube surface under stress

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If frequent inspections are conducted to monitor diametrical growth, then reliability of remaining life prediction improves, but loss of time and operational disruption increases

Engineering Contradiction:

Improveremaining life prediction accuracyVSAvoidinspection and shutdown time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

Reference markings are established during manufacturing or before service, creating permanent reference features that remain valid throughout the tube's operational life. This preliminary action enables accurate measurements to be taken at any inspection interval without requiring frequent recalibration or repeated complex setup procedures, thereby reducing the need for frequent shutdowns while maintaining prediction reliability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The reference markings provide stable feedback features that enable consistent measurement of diametrical growth over time. By comparing diameter measurements at different inspection intervals against the same reference markings, the system accumulates reliable data on creep strain and diametrical growth rates, improving remaining life prediction accuracy without requiring frequent inspections

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS10767980B2Method of determining diametrical growth of reformer tubes

Publication Date: 2020.09.08 PRAXAIR TECH INC

AI summary

The present invention relates to modifying a reformer tube to facilitate regular tube inspections to assess the service life and subsequently predict its remaining life accurately.